1. Field of the Invention:
This invention relates to electrical transformers and circuits employing the same, and more particularly to transformers having a specially configured core contributing to the desired input to output transformation ratio and permitting the simplification of the associated winding structure to facilitate inclusion thereof in power inverter circuits.
2. Prior Art:
Customarily, an electrical transformer comprises a magnetic flux path defining core, and input and output windings linking the flux carried by that core, with the input to output transformation (voltage and current) being determined by the turns ratio of the input and output windings. In many cases it is desirable to have an output winding consisting of a single turn for ease of fabrication. An example is seen in high current output transformers where the secondary may be made from thick bar-like conductor material which is impractical to form into multiple turns.
Moreover, high current output secondary windings in a power transformer may generate significant heat which must be transferred to adjacent structures. For this reason it is desirable to form the secondary winding as a simple, flat structure having an abundant heat transfer surface. This cooling requirement militates against provision of plural turns in such a winding. If traditional single flux turn magnetic structures are used, this single turn secondary winding requirement places design constraints on the primary winding for a given transformation ratio objective.
There are cases in which it is necessary to provide a center tap to a transformer winding. In prior art, such a center tap has always required a multiple turn winding. A well-known example is a "bridge transformer" having a primary connected in first and opposite directions, in alternation, across a d.c. bulk voltage source, and a secondary winding having a center tap connected to one side of the load, such as ground, and winding ends connected through respective diodes to the other side of the load to supply the same in push-push fashion. In high secondary current designs, it can be difficult to make the required connections to the secondary in a manner whereby they do not interfere mechanically or electrically with each other and wherein the diodes are packaged close to the secondary winding structure. In particular, the three connections exiting together from a conventional bridge transformer make it very difficult to contain the entire diode-diode commutate current loop within the transformer.